ENCELADUS FLYBY Scott Coughlin Brian Lach Holden Martin
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Outline 1. Background 2. Applications for Life Geological
Structure Tiger Stripes Chemicals Found 3. Previous Flyby Missions
Voyager 1 and 2 Cassini 4. Cassini 2.0 New Approaches New
Technology 5. Logistics Cost/Budget
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Background Enceladus is Saturns 14 th moon in terms of distance
Enceladus is 500 km in diameter making it Saturns sixth largest
moon Enceladus travel in Saturns E- Ring
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Some More Background!
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Saturns E-Ring Enceladus circles with Saturns E-ring and many
people believe that the water jets (or plumes) that come from
Enceladus actually are the cause of Saturns E-ring Numerous
mathematical models show that such a ring is unstable, with a
lifespan between 10,000 and 1,000,000 years. Therefore, particles
composing it must be constantly replenished. Enceladus is orbiting
inside this ring, in a place where it is narrowest but present in
its highest density.
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Geological Features 1.) Silicate Core 2.) Outer water-ice-rich
mantle 3.) Plate Tectonics 4.) Diapir 5.) Giant Plumes/Geysers 6.)
Tiger Stripes In south polar regions Warmest part of planet
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Why Enceladus? In May 2011 NASA scientists at an Enceladus
Focus Group Conference reported that Enceladus "is emerging as the
most habitable spot beyond Earth in the Solar System for life as we
know it. Properties: Liquid water, organic carbon, nitrogen [in the
form of ammonia], and an energy source. This is key because
according to Chris McKay, an astrobiologist at NASA's Ames Research
Center, besides Earth, "there is no other environment in the Solar
System where we can make all those claims."
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The Plumes Dramatic plumes, both large and small, spray water
ice out from many locations along the tiger stripes near the south
pole of Saturn's moon Enceladus. From right to left, the four major
stripes are Damascus, Baghdad, Cairo and Alexandria sulci.
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Analysis of Plumes Jack Hunter (J.H.) Waite, of the Southwest
Research Institute in San Antonio, Texas and his colleagues say
ammonia detected in the jets from Enceladus south pole provides the
strongest evidence yet for the existence of liquid water beneath
the surface. Analyses of Cassini through the heart of the plumes
show that 99% of the mass of plume ice-particles is salt-rich. This
implies that the water in plume ice came from salty liquid water
somewhere beneath the surface, say researchers. Below is the
chemical measurement of one of these plumes. This is a chemical
measurement contains all of the three things mentioned earlier:
Liquid water, organic carbon, nitrogen.
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Tiger Stripes
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More on Tiger Stripes April 14, 2012- The Fields, Particles and
Waves instruments (a.k.a. MAPS) are prime (particularly the ion and
neutral mass spectrometer [INMS]) to study the composition,
density, three- dimensional structure and variability of plumes;
with E-14, and E- 17, this flyby provides good coverage of south
polar regions. The Tiger Stripes
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How Hot is Hot? -140 F or -90 C May seem cold but is about 270
degrees warmer then the rest of the planet It is formed through a
combination of tidal heating and pressurized liquid which then
shoots out water vapor and ice particles
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Previous Missions Voyager 1 and 2 Launched in 1977. Flew by
Saturn system in 1980 and 1981, respectively. First to place
Enceladus on the map for possible places of life in our solar
system. Cassini Launched October 15, 1997. Flown by Enceladus 33
times an average of 34480 km away but with some flybys as close as
25 km. Most recent just yesterday May 2, 2012.
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Voyager 1 and Voyager 2 In the early 1980s, the two Voyager
spacecrafts passed Enceladus and found essentially all of the basic
background information stated earlier. 500 km in diameter Surface
reflected almost 100 percent of sun light, etc. Voyager 1 and 2
were important because they catapulted Enceladus to the forefront
of prospective places for life in our solar system.
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Cassini-Huygens Objectives regarding Enceladus: Determine the
characteristics and geological history of Enceladus Determine the
different physical processes that created the surface of Enceladus
Investigate composition and distribution of surface materials on
Enceladus particularly dark, organic material, and condensed ice
Determine the bulk composition and internal structure of Enceladus
Investigate interaction of Enceladus with Saturns magnetosphere and
ring system
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First Flybys July 14 & March 9, 2005 During the first two
close flybys (175km & 500km) of Enceladus, Cassini discovered a
deflection in the local magnetic field, and measurements taken
pointed to ionized water vapor as the main component. Cassini
observed water ice geysers erupting from the south pole, giving
credibility to the idea that Enceladus supplies the particles of
Saturns E ring. It was hypothesized that pockets of liquid water
exist near the surface making Enceladus one of the few bodies in
the solar system to contain liquid water.
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Second Flyby March 12, 2008 This close flyby (within 50km of
the surface) passed through the plumes of Enceladus southern
geysers and detected water, carbon dioxide, and various
hydrocarbons using a mass spectrometer. This flyby also involved
mapping surface features that were at a much higher temperature
than their surroundings with an infrared spectrometer. A cosmic
dust analyzer was intended to be used to collect data, but
malfunctioned.
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Third Flyby November 21, 2009 The third flyby came within
1600km of the surface. The composite infrared spectograph (CIRS)
was expected to map thermal emission from the tiger stripe Baghdad
Sulcus. Data and images returned were expected to help create the
most detailed image of the southern part of the moons Saturn facing
hemisphere and a contiguous thermal map of one of the tiger stripe
features. Image of Baghdad Sulcus
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May 2, 2012 Flybys are happening continually even as recent as
yesterday! This flyby is a radio science (RSS) gravity flyby, which
is designed to understand the internal structure of Enceladus,
particularly the concentration of mass under the south polar
region. RSS will have its usual three periods of observation: two
wings and closest-approach. The MAPS pointing will be optimized to
gather data near closest approach.
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New Discoveries Cassini has been doing wonders for data
collection about Enceladus. Information concerning the plumes has
all come from Cassini. Infrared imaging has allowed a new model of
the interior temperature and design of Enceladus to be made. M ost
importantly it has affirmed that there is most likely liquid water
on Enceladus, the most important discovery for a planet to
potentially have life. NASA provides daily images from Cassini
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What Can Be Done? Cassini 2.0 Cassinis instruments only
revealed basic information concerning the prospects of life. New
instruments would help confirm findings about the plumes and the
hot spots.
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Possible Approaches One-way mission: Multiple flybys of
Enceladus and other moons Crash the orbiter at end of mission
Lander probe (Huygens probe)
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Other Approaches Round-trip flight: More focused mission to
collect plume material Analyze plume material in lab on Earth
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Getting there (and maybe back) 1.2 billion km (~8 AU) to Saturn
at closest point Cassini: 7 years travel time at up to 45 km/sec
Getting there: multiple gravity boosts from Venus, Earth, and
Jupiter reduces travel time Requires special alignment of planets;
small launch window
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Staying there: Engine to slow spacecraft into Saturns orbit
Steer mainly with Titan flybys Getting Back: More gravity boosts!
Extra weight for heat shield, parachute, fuel
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Purpose of Cassini 2.0 Assess astrobiological potential and
geology of Enceladus Plumes and E-ring: Confirm liquid water is
source of plumes Look for biomarkers, elements for life ex: confirm
fraction of CO vs. N 2 vs. hydrocarbons Further study of Enceladus
surface
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Titan Saturn System Mission (TSSM) Joint NASA/ESA proposal for
an exploration of Saturn, Titan, and Enceladus Minimum of seven
close Enceladus flybys Exploring the composition of the Enceladus
plumes and whether the source region is liquid water
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Cassini Instruments Optical remote sensing- detect
electromagnetic light (infrared, visible, and ultraviolet; low- and
high-res) Fields, particles, and waves- study dust (plumes),
plasma, and magnetic fields Microwave remote sensing- use radio
waves to map atmospheres and surface
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Cassini 2.0 Instruments ROSINA (Rosetta Orbiter Spectrometer
for Ion and Neutral Analysis) Mass Spectrometer Reveal chemical
composition of Enceladus plumes Characterize complex organic
molecules with a 10 larger mass range, 100 higher resolution, and
1000 better sensitivity than Cassini Search for biomarkers:
carbon-12,- 13 ratio
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Cassini 2.0 Instruments
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The Mission Launch 2016, arrive 2023 Multiple flybys of
Enceladus and Titan Sample different South pole plumes on
Enceladus, thermal mapping Cost: $500 million (Cassini: ~$2.5
billion)
